| The usage of mineral pigments has a long history in China and even the world.Although the kinds of minerals that can be used as pigments are limited,the color appearance of mineral pigments will change accordingly with the change of the particle size of mineral pigment particles.This characteristic of mineral pigments greatly enriches the colors of mineral pigments and expands the color system of mineral pigments.At the same time,it also deeply affects the production,application and research of mineral pigments.In the modern production process of the mineral pigments,the particle sizes of pigment particles were graded more finely,which is bound to improve the color quality of mineral pigment.In the creation of modern rock color paintings,painters pay more attention to the color matching and the material selection of mineral pigments.These will make painters want to select and use the particle size of pigments more accurately.When performing high-quality restoration of the color appearance of the rock color paintings of cultural relics,it is very important to accurately obtain the particle size information of mineral pigment layer of the painted cultural relics.In summary,the particle size of mineral pigment particles plays an increasingly important role in the production,application and scientific research of mineral pigments,and is an indispensable physical quantity in the painting and scientific research.A numbers of studies have been conducted to investigate the relationship between the particle size of mineral pigments and their color appearance.However,how the particle size of mineral pigment influence their color appearance is still unknown.As we all know,the color of an object is the result of the interaction between light and matter.The color appearance of an object depends on the spectral characteristics of that.However,there is a lack of optical theoretical study to investigate how the change of the particle size affects the spectral reflectance information of the mineral pigments.At the same time,in the application of mineral pigment particle size estimation based on spectral information matching,if the spectral reflectance of mineral pigment which used for estimate particle size is interfered by other spectral information,the matching accuracy between the measured spectral reflectance and the standard spectral reflectance containing the particle size information is easily affected.This problem still needs to be solved.Therefore,this thesis attempts to carry out research work around these two issues about the mineral pigment particle size.Above all,an optical physical model is established for mineral pigment used in rock color painting to analyze the influence mechanism of how the particle size change of mineral pigment affects their spectral reflection and color appearance.This is helpful for people to understand the mechanism of the particle size influenced on the color appearance and spectral reflectance of mineral pigments,and also provides theoretical base or results reference for conducting a comprehensive and systematic study on the optical theory of mineral pigments in the future.Moreover,the precise control research of the relationship between the particle size and the color appearance in the mineral pigment production industry,and the application and theoretical research about mineral pigments all will benefit from this.Next,the ratio derivative spectral analysis method is applied to the processing of the disturbed spectral reflectance of the mineral pigment.This method can suppress the influence from the disturbed spectral information,and enhance the spectral characteristic information of the mineral pigment.Then,the accuracy matching between the measured spectral reflectance and the standard spectral reflectance containing the particle size information is realized.In the application of estimating the particle size information of mineral pigments on mural surface,it provides a reference method for analysis and processing of the similar disturbed spectral reflectance data.For these purposes,this thesis carries out the following three parts of the work.Firstly,the influence of the particle size change on the spectral reflectance of mineral pigment color block is analyzed.According to the usage method of mineral pigments and the physical characteristics of mineral pigment color blocks,based on the optical principles,the optical characteristics and laws of the interaction between light and the mineral pigment particles of the color blocks are analyzed.Then,an optical physical model suitable for discussing the influence of particle size change on the spectral reflectance of mineral pigment color blocks is established.The model confirms that the reflected light of the mineral pigment color block is composed of two parts: the reflected light from the first surface of the color block and the body diffuse reflected light emitted from the pigment layer of the color block.Then,the influence of the particle size change on the formation process of the two parts reflected light is deeply studied,and the influence mechanism and influence law of the particle size change on the spectral reflectance of the mineral pigment color block are revealed.Secondly,the influence of the particle size change on the color appearance of mineral pigment color block is analyzed.The color is essentially the result of the interaction between light and matter.Based on the colorimetry theory and the research results of the first part work,the influence of the particle size change on the color appearance of mineral pigment color block is studied.The spectral measurement values of the mineral pigment color blocks are converted into the colorimetric values.According to the theory of conversion process,how the influence of the particle size change on the spectral reflectance is transferred to the color values is analyzed.The reason and law of the influence of the particle size change on the color values are revealed.Then,the experimental results are analyzed theoretically.The theoretical analysis and experimental results confirmed that the usage of mineral pigment by particle size grading plays a key role in the expansion of the mineral pigment color system.Finally,in the application of estimating mineral pigment particle size information based on spectral matching results,when the measured spectral reflectance of mineral pigment color block is disturbed by other spectral information,how to match the measured spectral reflectance with the standard spectral reflectance containing particle size information accurately is the third part work.The simulated color block samples were made,and the disturbed spectral reflectance of the color block samples were obtained.Then,the disturbed spectral reflectance is analyzed by the ratio derivative spectral method.The influence of the disturbed information is suppressed in the ratio derivative spectral space to achieve the effective matching between the disturbed spectral reflectance of the mineral pigment color block and standard spectral reflectance containing particle size information.This method can provide a reference method for analysis of disturbed spectral reflectance in the application area of mineral pigment particle size estimation. |
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